Infants of mothers with primary hypothyroidism are generally not at risk of hypothyroidism.

These infants will normally have their TSH checked at day 5 as part of the newborn screening programme.

No further testing is generally required.

Caution should be exercised if the cause of the maternal hypothyroidism is unknown, as the mother may have been treated for hyperthyroidism previously and had become hypothyroid.

If in doubt it is wise to assume the mother may have been hyperthyroid and that the mother may have thyroid antibodies.